Abstract

The objective of this study was to replicate the three-factor structure of the Need for Sexual Intimacy Scale (NSIS; Marelich & Lundquist, 2008; Marelich & Shelton, 2011), and evaluate correlations of the NSIS subscales with intimacy-related measures. Participants were 422 individuals from a large, ethnically diverse Southern California university. Results confirmed the NSIS subscale structure (need for sex, need for dominance, and need for affiliation), as was a latent second-order factor for sexual intimacy. Individuals with a higher need for sex had higher levels of sexual desire, more unrestricted sexual attitudes, and higher sexual awareness. Those reporting a higher need for dominance engaged in more dominant behaviors, and those reporting a higher need for affiliation had more positive attitudes about emotional support and closeness in relationships. Males reported a higher need for sex and dominance than females. Overall, the NSIS appears to be a viable measure of sexual intimacy motivations, inclusive of the needs for sex, dominance, and affiliation. Prior research had shown the measure to agree with pervasive sexual behaviors, and the current research further validates the scales through associations with intimacy-related measures. One caveat of the current paper is that the results are based on a Psychology college student sample; therefore the results may not fully generalize to other populations.

Correlates Factor and Factor Replication of the Need for Sexual Intimacy Scale (NSIS)

When thinking of sexual intimacy, desires and motivations for sex are often first considered (e.g., Knox, Sturdivant, & Zusman, 2001; Motley & Reeder, 1995). Yet, sexual intimacy may be viewed as a broader concept beyond sexuality, incorporating factors that together form a broader sexual intimacy construct. Indeed, both theoretical and empirical research shows that sexual intimacy is a confluence of additional concepts. For example, motivations for sexual intimacy have been shown to include not only desires for sex, but also desires for partner compliance (Hoffman & Bolton, 1997), commitment/love (Carroll, Volk, & Hyde, 1985), power (Falbo & Peplau, 1980; Hill & Preston, 1996; Starratt, Popp, & Shakelford, 2008), affiliation (McAdams & Powers, 1981), and closeness (Meston & Buss, 2007). Given the continued elevated rates of newly diagnosed sexually transmitted diseases in the U.S. (approximately 19 million news cases per year, costing an estimated 17 billion dollars; Centers for Disease Control and Prevention, 2011) and continued prevalence of high risk sexual behaviors (e.g., Chandra, Mosher, Copen, & Sionean, 2011; Herbenick et al., 2010; Owen, Rhoades, Stanley, & Fincham, 2010), a valid and reliable measure for sexual intimacy needs is paramount for understanding underlying motivational drives and sexual awareness.

In an effort to more fully consider sexual intimacy motivations, Marelich and Lundquist (2008) developed the three factor Sexual Intimacy Scale (NSIS), focusing on three facets of sexual intimacy -- sex, dominance, and affiliation. Theoretically, the NSIS is based on sexual intimacy needs taken from Murray (1938/2008). The needs of sex, affiliation, and dominance were chosen as conceptual anchors based on their definitional properties with sexual intimacy. Murray (1938/2008, p. 167) defines the need for sex as the “format[ion] and further[ing] of an erotic relationship. To have sexual intercourse.” The second sexual intimacy aspect was affiliation, defined as the desire “to draw near and enjoyably co-operate or reciprocate with an allied [other] . . .To please and win affection of a cathected [other]” (p. 174). Dominance was also chosen per its definition as the need to “to control one’s human environment. To influence or direct the behaviour of [others] by suggestion, seduction, persuasion, or command” (p. 152). Beyond Murray, different combinations of these needs have been shown to be associated with motivations for intimacy, closeness and sexuality (e.g., Maslow, 1943; McAdams & Powers, 1981; Meston & Buss, 2007; Moss & Schwebel, 1993; Schultheiss, Dargel, & Rohde, 2003; Sternberg, 1986; Yost & Zurbriggen, 2006).

Marelich and Lundquist (2008) showed the NSIS subscales correlated well with various sexual health and intimacy related behaviors (e.g., number of sexual partners, condom use, deception regarding STIs, sexual communication). However, their assessment included only behavioral outcomes associated with sexual intimacy, neglecting broader established measures of sexual desires/motivations, affiliation, and dominance. The current paper with a new sample addresses this deficit by investigating associations of the NSIS with established scales reflecting its underlying constructs, and to replicate the NSIS factor structure.

Overall, we expect the original factor structure of the NSIS to be confirmed (using confirmatory factor analysis) with good internal consistency reliability, including its second-order structure. In addition, the NSIS subscales will show associations with the measures noted above. Specifically, higher scores on the NSIS need for sex subscale will be associated with positive sexual attitudes, motivations, and behaviors (measured through the SOI, SAQ, CPA, SDI, and SAF), and will be less likely to exhibit an Eros love style. Those with higher scores on the NSIS need for dominance subscale will exhibit greater dominance as measured on the IPIP, greater SAQ sexual assertiveness, and will be more likely to show Ludus and Mania love styles. Higher scores on the NSIS need for affiliation subscale will be associated with lower scores on casual sexual attitudes and behaviors (i.e., SOI, CPA). Those higher in need for affiliation will also reflect higher scores on the IOS subscales addressing affiliative motivations, including emotional support and positive stimulation, and will also exhibit Eros, Pragma, and Agape love styles, but less likely to report a game-playing love style.

Method

Participants
Participants were 422 students enrolled at a large Southern California University, recruited from introductory and upper division psychology courses. Participants were at least 18 years of age and reported at least one sexual intercourse partner in their lifetime. The mean number of lifetime sexual intercourse partners was 5.69, with a standard deviation of 13.17, and a median of 3. Overall, 57.8% of the sample reporting 1-3 sexual intercourse partners, 19.7% reporting 4-6 partners, 14% reporting 7-10 partners, and 8.5% reporting more than 10 partners. Participants were primarily female (65.4%) with ages ranging from 18-46 years (Mean = 20.71, SD = 3.75, median = 19). Of the participants in the sample, 40.8% identified themselves as White, 5.2% identified themselves as African American, 25.6% identified themselves as Latino, 14.7% identified themselves as Asian American, and 12.3% self-identified as Other/Mixed race.

The majority of participants reported at least casually dating someone at the time of the study (67.8%), with 8.3% reporting being engaged/married, and 22% not dating anyone. Although the latter percentage may seem high, it appears in line with other recently published accounts of dating status (e.g., Paik, 2010), and may reflect the slow growth of casual sex hookups and friends with benefits relationships (e.g., Grello, Welsh, & Harper, 2006; Hughes, Morrison, & Asada, 2005; Johnson et al., 2007) compared to more traditional relationship pairings.

Measures

Need for Sexual Intimacy

The Need for Sexual Intimacy Scale (NSIS; Marelich & Lundquist, 2008; Marelich & Shelton, 2011) is the main measure addressed in the current study, and is divided into three subscales addressing the needs for sex, affiliation, and dominance. Participants rated 22 needs-based items on a scale of 1 (disagree definitely) to 5 (agree definitely). Higher scores on the subscales indicate greater needs for sex, affiliation, and dominance. Example items for need for sex include the need "...to have more sex", and "...to let myself go sexually with someone." Example items for need for affiliation include the need to have "...someone to love", and to have "...a companion in life." Example items for need for dominance include the need to have "...control over my partner", and to have "...a partner I can manipulate." A full set of the NSIS items may be found in Marelich and Shelton (2011). Current sample reliabilities for these subscales are presented in the Results.

The Casual Physical Acquaintance Scale (CPA; Johnson et al., 2007) is a self report attitudinal scale assessing attitudes and beliefs about “friends with benefits” relationships. The measure may be broken into three subscales (personal attitudes, subjective norms, and perceived personal control) and a total score. For the current study, we utilized the total CPA score and the attitude subscale. Current sample reliability was .70 for the overall CPA measure, and .71 for the 3-item attitude measure (higher scores indicate more positive attitudes toward CPA or “friends with benefits” relationships).

The Dominance Scale from the International Personality Item Pool (IPIP) is utilized to assess dominance-related issues (Goldberg et al., 2006). The IPIP Dominance Scale addresses individual behaviors which show dominance. Higher scores indicate greater levels of dominance. Cronbach’s alpha for the current sample was .77.

The Interpersonal Orientation Scale (IOS; Hill, 1987) was utilized to assess motivations for affiliation. It consists of four subscales, two of which will be utilized for the purposes of this study. The two subscales chosen, emotional support and positive stimulation, were selected based on their similarities with the NSIS affiliation subscale. Higher scores indicate greater emotional support and stimulation. Current sample internal consistency reliability for emotional support was .89, and .87 for positive stimulation.

We also use the Short Form Love Attitudes Scale (LAS; Hendrick et al., 1998), which measures love styles, including Eros, Ludus, Storge, Pragma, Mania, and Agape. In their original article, lower scores for each love style indicate that the individual subscribes to that style (for the current study, we reverse-coded the love style scores so that higher values would indicate the preferred love style). Current sample reliabilities were .76 for Eros, .60 for Ludus, .88 for Storge, .82 for Pragma, .74 for Mania, and .86 for Agape.

Procedure

Individuals who chose to participate in the study for introductory psychology course research credit were able to volunteer through an on-line research registration database (IRB approval for the study was obtained through the hosting University). Once a survey time was chosen, participants arrived to an assigned research room to complete the questionnaire packet (including an Informed Consent page), placing the completed questionnaire in a designated drop-box as they exited the research room. Individuals from other courses (e.g., a social psychology course) could also participate and receive research credit, or complete the survey without credit, by obtaining a questionnaire packet from their instructor, completing the packet at home, and returning the packet to a designated laboratory drop-box.

Analyses

Confirmatory factor analysis was performed using EQS (Bentler, 2006) to validate the existing factor structure of the NSIS and second-order latent construct. Polychoric correlations were used given the ordinal nature of the scale measurement (Coenders, Satorra, & Saris, 1997; see Bentler, 2006, for application in EQS). Both Spearman's rho and Pearson's r were used to assess the relationships between the NSIS scales and intimacy measures at the p </= .01 level (Somers' D, and Goodman and Kruskal's Gamma were also evaluated). Effect sizes are reported based on recommendations by Cohen (1992).

Results

Confirmatory factor analysis (CFA) with a maximum likelihood solution was conducted to validate the NSIS factor structure utilizing polychoric correlations to address the ordinal nature of the NSIS scale. Robust estimation was used to address any violations of multivariate normality (Bentler, 2006), and the model applied was the original NSIS factor structure from Marelich and Lundquist (2008). Factor error variances on the measured variables were fixed at 1.0 for identification purposes. All other factor loadings and latent factor correlations were free to vary. Items were forced to load only on their respective factors per Marelich and Lundquist, including a cross-loading for the item [Need] someone to sleep next to me, which was allowed to cross-load on the Need for Sex and Need for Affiliation. Model fit was evaluated by assessing multiple robust fit indices, including the comparative fit index (CFI), the incremental fit index (IFI), and the root mean square error of approximation (RMSEA).

The resulting model using robust fit showed a Satorra-Bentler χ2 = 594.56 (205, N = 422), with a CFI of .93, an IFI of .93, and a RMSEA of .067 (90% C.I. = .061 to .073). No additional model fit was undertaken. All parameter estimates were significant at the p < .001 level (similar to those published on a different dataset; see Marelich & Lundquist, 2008). Factor correlations produced as part of the polychoric matrices were found between Need for Sex and Need for Dominance, r(422) = .47, p < .001, and Need for Dominance and Need for Affiliation, r(422) = .11, p = .06. The correlation between Need for Sex and Need for Affiliation was approximately zero, r(422) = -.03, n.s. Internal consistent reliabilities using the polychoric associations and reliability coefficient rho (based on a one factor latent model approach and similar to McDonald's coefficient omega; see Bentler, 2006) were .88, .76, and .85 (for Need for Sex, Need for Dominance, and Need for Affiliation, respectively), and for comparative purposes, Cronbach’s alphas for the three subscales were .88, .76, and .84 (respectively).

A second-order CFA was also conducted adding the latent factor Need for Sexual Intimacy following Marelich and Lundquist (2008), and performed due to the construct correlations just reported. The second-order factor variance was set to 1.0, and paths from this factor to the first-order factors were estimated as were their disturbance terms. Per Byrne (1994), (a) first-order factor covariances were removed, (b) one item from each first-order factor was fixed to 1.0 for identification purposes, and (c) the disturbance terms from Need for Sex and Need for Dominance were constrained (otherwise, the second-order model would be "just-identified" providing the same exact fit as the first-order model).

As noted in Table 1, Spearman rho (used due to the ordinal nature of the data) and Pearson correlations (retained for comparative purposes) show significant relationships between the need for sex subscale and measures associated with sexuality and desire (note that both Somers' D, and Goodman and Kruskal's Gamma results match the rho significance findings and therefore are not reported). Those more likely to have an unrestricted sexual orientation, and have more positive attitudes toward friends with benefits relationships, also report having a greater need for sex (both associations with at least medium effects based on r; see Cohen, 1992). All SAQ and SDI subscales, and the sexual attitudes and feelings measure, were found to be significantly associated with the need for sex, indicating greater sexual awareness, sexual consciousness, and sexual desire were associated with a greater need for sex (with most exhibiting at least a medium effect). Romantic love (Eros) was found to be negatively associated with need for sex (a small effect), while game-playing love style (Ludus) was positively associated, indicating those who prefer a game-playing love style report a higher need for sex (a medium effect). Men (Mean = 2.88, SD = 0.79) reported a higher need for sex than women (Mean = 2.31, SD = 0.82), t(415) = 6.74, p < .001.

Need for dominance, though correlated with need for sex, showed a distinct pattern of correlations with many of the measures. For the SOI and the CPA, no associations were noted, agreeing with the intent of these scales which focus on unrestricted sexuality and openness to sex, not sexual dominance. IPIP dominance showed a positive correlation with need for dominance, with those higher on IPIP dominance reporting a greater need for sexual intimacy dominance (a small to medium effect). The IOS positive stimulation subscale also showed a significant (but small) association with need for dominance. For the LAS subscales, Ludus (game playing) and Mania (possessive/dependent) showed significant associations in line with hypothesized associations (small and medium effects). Pragma (logical love style) also showed a significant positive correlation with dominance with a small to medium effect. No gender differences were noted between men (Mean = 1.94, SD = 0.72) and women (Mean = 1.92, SD = 0.70), t(415) = 0.31, n.s.

As expected, need for affiliation was negatively associated with the SOI and CPA – those having a higher need for affiliation tended to have negative attitudes and behaviors toward casual sexual experiences (medium effects). None of the SDI subscales, or the dominance-related IPIP subscale reached significance, and the SAQ subscale addressing sexual monitoring showed a significant Spearman rho. The IOS emotional support and positive stimulation subscales did show positive associations, suggesting that those with a higher need for affiliation reported providing more emotional support and positive stimulation (small to medium effects). For the LAS subscales, Eros (romantic/passionate), Pragma (logical), Mania (possessive/dependent), and Agape (selfless) all showed positive associations with need for affiliation (medium effects), while Ludus (game playing) love style had a negative association (small to medium effect). Women (Mean = 4.13, SD = 0.54) reported a higher need for affiliation than did men (Mean = 3.87, SD = 0.69), t(415) = 4.32, p < .001.

To limit space, we present briefly in the Discussion correlations of the NSIS subscales with various sexual health behavior items (with similar findings as noted by Marelich and Lundquist, 2008), which may be viewed as more applied in nature since they address directly sexual and sexual-health related behaviors.

Discussion

The NSIS appears to be a viable measure of sexual intimacy motivations, inclusive of the needs for sex, dominance, and affiliation. Advantages of the NSIS over other measures include its theoretical foundation based on Murray’s needs framework (1938/2008) and assessment of multiple sexual-intimacy facets. At 22-items, the NSIS is an economical measure that may be added to broader relationship and sexuality assessments to assess needs associated with sexual intimacy, offering a unique theory-based insight into sexual intimacy motivations.

The current paper adds to the literature by illustrating the correlates of the NSIS with intimacy-related measures reflecting sexuality, and other measures assessing affiliation and dominance. In addition, the study underscores that sexual intimacy may be viewed as the confluence of additional factors beyond basic needs for sex. For example, Peplau, Rubin, and Hill (1977) illustrate how sexual intimacy entails factors beyond sex, including emotional bonds similar need for affiliation. Similarly, Gilmartin (2006) notes how intimacy incorporates sex, affection, and intimacy. Leigh (1989) notes that issues of conquest are often mentioned when individuals are asked why they have sex, thus underscoring how dominance is incorporated into sexual intimacy motives (emotional closeness is also noted as a reason for having sex). Further, Zubriggen and Yost (2004) note that sexual intimacy fantasies often incorporate issues of partner dominance.

Use of NSIS can help researchers in the human sexuality and close relationship fields explore intimacy needs and their subsequent behavioral outcomes. For example, the NSIS can be used to improve the sexual awareness of individuals, especially teens and young adults who are sexually active. Past research with the NSIS showed that a higher need for sex was associated with more risky sexual behaviors, including one night stands, lack of condom use, and lying about having an HIV test, while those higher in need for affiliation under-report their total number of sexual partners (Marelich & Lundquist, 2008). Although not reported in the Results (to limit space), the current study exhibits similar associations. Both Spearman and Pearson correlations show those higher in need for sex are significantly (p < .05) less likely to discuss being HIV-tested or safe-sex, have more sex partners and one-night stands, less likely to use condoms, more likely to use intoxicants during sex, and more likely to have ever had an STD. Those higher in dominance are less likely use condoms (Pearson r only at p = .05), or discuss safe-sex with their partners, and more likely to use intoxicants as part of a sexual encounter (r only). Those higher in the need for affiliation report fewer lifetime sexual partners, and are less likely to use condoms.

Based on the findings from the main analyses, higher needs for sex are associated with a greater propensity toward positive attitudes and behaviors for casual sex, friends with benefits situations, and sexual desires, and higher needs for dominance lead to a greater tendency for a game-playing love styles and dominant behaviors. With this information (and those noted above regarding sexual health behaviors), researchers can implement primary prevention programs (e.g., Belenko, Dembo, Rollie, Childs, Salvatore, 2009; DiClemente et al., 2008; Kaplan, 2000) to help educate individuals about their intimacy needs and how such needs influence risky-sexual attitudes and behaviors. For example, those reporting greater sexual-intimacy motivations needs in the current study also report lack of condom use, poor sexual communication, and use of intoxicants during the sexual encounter. Although interventions aimed to reduce intoxicant use (i.e., alcohol) do not necessarily reduce risky sexual behaviors (e.g., Dermen & Thomas, 2011), those that instead focus on safe-sex practices and sexual communication do indeed have a positive impact (Davey-Rothwell, Tobin, Yang, Sun, & Latkin, 2011; Johnson, Scott-Sheldon, Huedo-Melina, & Carey, 2011; Noar, Carlyle, & Cole, 2006).

There are several limitations to the current study. Our results are based on a sample of Psychology college students and therefore may not generalize well to other populations (e.g., other disciplines, non-college populations). The sample is also relatively young, and an individual’s sexual intimacy needs may change as a function of age and/or relationship status. Another limitation regards our effect size statistic (Pearson's r); the sizes reported should be interpreted as suggestive given the ordinal nature of some of our variables. Another caveat is the cross-sectional nature of the data. Future research should consider a longitudinal design to assess whether these needs grow or decline, and how such variability may affect intimacy. Future validation efforts of the NSIS should also be inclusive of other validation techniques beyond structural equation modeling applications. In particular, multidimensional scaling (MDS) could be utilized to evaluate the structure of the NSIS items (cf. Tucker-Drob & Salthouse, 2009).